Co-doped ZnO-Ga2O3-SiO2 nano-glass-ceramic composites were prepared by sol-gel method. X-ray diffraction patterns showed that the crystallization temperature was 800 degrees C. X-ray photoelectron spectroscopy (XPS) was used to study the effect of heat-treatment temperature on the electronic structure of Co-doped ZnO-Ga2O3-SiO2 nano-glass-ceramic composites. The Zn (2p(3/2)), Ga (2p(3/2)) and O (1s) XPS spectra for the glass-ceramics heat-treated at 800-1000 degrees C could be deconvoluted into two peaks corresponding to these elements in glass network and in nanocrystals, respectively. The results indicate that the material is composed of an amorphous silicate network and ZnGa2O4 nanocrystalline particles. The amount of nanocrystals increases with the annealing temperature. The photoelectron peak of Si (2p) shifts to higher binding energy at higher annealing temperature, revealing the charge transfer from Si to O increased. The relationship between the microstructure of Co-doped ZnO-Ga2O3-SiO2 sample and its absorption properties was discussed, and the suitable heat-treatment temperature was proposed. (c) 2010 Elsevier B.V. All rights reserved.